U.S. patent application number 13/242822 was filed with the patent office on 2013-03-28 for system and method for combining co-located flowmeters.
This patent application is currently assigned to DANIEL MEASUREMENT AND CONTROL, INC.. The applicant listed for this patent is Graham W. FORBES, Kerry D. GROESCHEL. Invention is credited to Graham W. FORBES, Kerry D. GROESCHEL.
Application Number | 20130080080 13/242822 |
Document ID | / |
Family ID | 47912199 |
Filed Date | 2013-03-28 |
United States Patent
Application |
20130080080 |
Kind Code |
A1 |
FORBES; Graham W. ; et
al. |
March 28, 2013 |
SYSTEM AND METHOD FOR COMBINING CO-LOCATED FLOWMETERS
Abstract
A system and method for ultrasonic flow metering. In one
embodiment, an ultrasonic flow metering system includes a passage
for fluid flow and a plurality of ultrasonic flowmeters. Each of
the ultrasonic flowmeters includes a pair of ultrasonic
transducers, and a flow processor. The pair of ultrasonic
transducers is configured to form a chordal path across the passage
between the transducers. The flow processor is coupled to the
ultrasonic transducers. The flow processor is configured to measure
the fluid flow through the spool piece based on outputs of the
transducers of all of the ultrasonic flowmeters.
Inventors: |
FORBES; Graham W.; (Houston,
TX) ; GROESCHEL; Kerry D.; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FORBES; Graham W.
GROESCHEL; Kerry D. |
Houston
Houston |
TX
TX |
US
US |
|
|
Assignee: |
DANIEL MEASUREMENT AND CONTROL,
INC.
Houston
TX
|
Family ID: |
47912199 |
Appl. No.: |
13/242822 |
Filed: |
September 23, 2011 |
Current U.S.
Class: |
702/48 ;
73/861.28 |
Current CPC
Class: |
G01F 7/00 20130101; G01F
1/668 20130101; G01F 1/667 20130101 |
Class at
Publication: |
702/48 ;
73/861.28 |
International
Class: |
G01F 1/66 20060101
G01F001/66; G06F 19/00 20110101 G06F019/00 |
Claims
1. An ultrasonic flow metering system, comprising: a passage for
fluid flow; and a plurality of ultrasonic flowmeters, each
flowmeter comprising: a pair of ultrasonic transducers configured
to form a chordal path across the passage between the transducers;
and a flow processor coupled to the ultrasonic transducers, and
configured to measure the fluid flow through the passage based on
outputs of the transducers of all of the flowmeters.
2. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters further comprises a communication transceiver
configured to communicatively couple the flowmeter to each of the
other flowmeters of the plurality of flowmeters.
3. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters is configured to retrieve from each other flowmeter
of the plurality of flowmeters a measurement of flow velocity
determined by the other flowmeter; wherein the retrieval from each
other flowmeter is constrained to a periodic flow computation time
interval defined for each flowmeter.
4. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters is configured to compute a combined flow velocity
based on flow velocities retrieved from each of the other
flowmeters of the plurality of flowmeters.
5. The system of claim 4, wherein the combined flow velocity
comprises an average of the flow velocities retrieved from each of
the other flowmeters of the plurality of flowmeters.
6. The system of claim 4, wherein each flow processor is configured
to compute at least one of a corrected flow rate and an uncorrected
flow rate based on the combined flow velocity.
7. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters is configured to: determine whether flow velocities
provided to the flowmeter by other flowmeters of the plurality of
flowmeters are valid; and generate, based on a determination that a
flow velocity provided to the flowmeter is invalid, a flow
measurement based on only outputs of the transducers of the
flowmeter.
8. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters comprises a transducer controller that controls
timing of ultrasonic signal generation by the transducers of the
flowmeter; wherein the transducer controllers are configured to
synchronize ultrasonic signal generation over the plurality of
ultrasonic flowmeters.
9. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters comprises at least one sensor selected from a group
consisting of a temperature sensor, a pressure sensor, and a gas
composition sensor; and each flowmeter of the plurality of
flowmeters is configured to: retrieve from a different flowmeter of
the plurality of flowmeters a sensor measurement value derived from
the at least one sensor, and compute a combined flow rate based on
the sensor measurement value.
10. The system of claim 1, wherein each flowmeter of the plurality
of flowmeters comprises a given number of chordal paths, and the
flow processor of each flow meter of the plurality of flowmeters is
configured to compute a combined flow rate based on more than the
given number of chordal paths of the flowmeter.
11. A method for measuring fluid flow, comprising: determining, by
a first ultrasonic flowmeter, a first flow velocity of fluid
flowing through the first ultrasonic flowmeter; determining, by a
second ultrasonic flowmeter, a second flow velocity of fluid
flowing through the second ultrasonic flowmeter; and producing a
combined flow rate, by the first ultrasonic flowmeter, by combining
the first and second flow velocities.
12. The method of claim 11, further comprising retrieving, by the
first ultrasonic flowmeter, the second flow rate from the second
ultrasonic flowmeter.
13. The method of claim 11, wherein producing a combined flow rate
comprising determining at least one of a corrected flow rate and an
uncorrected flow rate.
14. The method of claim 11, further comprising determining an
average flow velocity based on the first flow velocity and the
second flow velocity.
15. The method of claim 11, further comprising generating, by the
first ultrasonic flowmeter, a flow rate of fluid flowing through
the first ultrasonic flowmeter, based only on measurements of fluid
flow through the first ultrasonic flowmeter, based on at least one
of the first ultrasonic flowmeter being unable to retrieve the
second flow rate from the second ultrasonic flowmeter and the
second flow rate being invalid.
16. The method of claim 11, further comprising generating a
synchronization signal, by the first ultrasonic flowmeter that
synchronizes generation of ultrasonic signals by a plurality of
transducers of the first and second ultrasonic signals.
17. The method of claim 11, further comprising generating by at
least one of the first and second ultrasonic meters a sensor
measurement comprising at least one of a temperature measurement, a
pressure measurement, and a gas composition measurement of fluid
flowing the flowmeter, and wherein the combined flow rate is based
on the sensor measurement.
18. A computer-readable medium encoded with instructions that when
executed cause a processor of an ultrasonic flowmeter to: determine
a first flow velocity of fluid flowing through the first ultrasonic
flowmeter; retrieve from a co-located ultrasonic flowmeter a second
flow velocity of fluid flowing through the co-located ultrasonic
flowmeter; and produce an average flow velocity by combining the
first and second flow velocities.
19. A computer-readable medium of claim 18, further comprising
instructions that when executed cause a processor of an ultrasonic
flowmeter to generate a combined flow rate based on the average
flow velocity.
20. A computer-readable medium of claim 18, further comprising
instructions that when executed cause a processor of an ultrasonic
flowmeter to generate a measurement of fluid volume flowing through
the ultrasonic flowmeter, based only on measurements of fluid flow
through the ultrasonic flowmeter, and based on at least one of the
ultrasonic flowmeter being unable to retrieve the second flow
velocity from the co-located ultrasonic flowmeter and the second
flow velocity being invalid.
20. A computer-readable medium of claim 18, further comprising
instructions that when executed cause a processor of an ultrasonic
flowmeter to generate a synchronization signal that synchronizes
generation of ultrasonic signals by a plurality of transducers of
the ultrasonic flowmeter and the co-located ultrasonic
flowmeter.
21. A computer-readable medium of claim 18, further comprising
instructions that when executed cause a processor of an ultrasonic
flowmeter to retrieve, from the co-located ultrasonic flowmeter, a
sensor measurement comprising at least one of a temperature
measurement, a pressure measurement, and a gas composition
measurement of fluid flowing through the co-located ultrasonic
flowmeter, and produce a combined flow rate based on the sensor
measurement.
Description
BACKGROUND
[0001] After hydrocarbons have been removed from the ground, the
fluid stream (e.g., crude oil, natural gas) is transported from
place-to-place via pipelines. It is desirable to know with accuracy
the amount of fluid flowing in the stream, and particular accuracy
is demanded when the fluid is changing hands, or "custody
transfer." Even where custody transfer is not taking place,
however, measurement accuracy is desirable, and in these situations
flowmeters may be used.
[0002] Ultrasonic flowmeters are one type of flowmeter that may be
used to measure the amount of fluid flowing in a pipeline. In an
ultrasonic flowmeter, ultrasonic signals are sent back and forth
across the fluid stream to be measured, and based on various
characteristics of the ultrasonic signals a measure of fluid flow
may be calculated. Ultrasonic flowmeters providing improved flow
measurement accuracy are desirable.
SUMMARY
[0003] A system and method for ultrasonic flow metering is
disclosed herein. In one embodiment, an ultrasonic flow metering
system includes a passage for fluid flow and a plurality of
ultrasonic flowmeters. Each of the ultrasonic flowmeters includes a
pair of ultrasonic transducers, and a flow processor. The pair of
ultrasonic transducers is configured to form a chordal path across
the passage between the transducers. The flow processor is coupled
to the ultrasonic transducers. The flow processor is configured to
measure the fluid flow through the spool piece based on outputs of
the transducers of all of the ultrasonic flowmeters.
[0004] In another embodiment, a method for measuring fluid flow
includes determining, by a first ultrasonic flowmeter, a first flow
velocity of fluid flowing through the first ultrasonic flowmeter. A
second ultrasonic flowmeter determines a second flow velocity of
fluid flowing through the second ultrasonic flowmeter. The first
ultrasonic flowmeter produces a combined flow rate by combining the
first and second flow velocities.
[0005] In a further embodiment, a computer-readable medium is
encoded with instructions that when executed cause a processor of
an ultrasonic flowmeter to determine a first flow velocity of fluid
flowing through the first ultrasonic flowmeter. Additional
instructions encoded on the medium cause the processor to retrieve
from a co-located ultrasonic flowmeter a second flow velocity of
fluid flowing through the co-located ultrasonic flowmeter. Yet
further instructions encoded on the medium cause the processor to
produce a combined flow rate by combining the first and second flow
velocities.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows an ultrasonic flowmeter in accordance with
various embodiments;
[0007] FIG. 2 shows a cross-sectional overhead view of an
ultrasonic flowmeter in accordance with various embodiments;
[0008] FIG. 3 shows an end elevation view of an ultrasonic
flowmeter in accordance with various embodiments;
[0009] FIG. 4 shows an arrangement of transducer pairs of an
ultrasonic flowmeter in accordance with various embodiments;
[0010] FIG. 5 shows a flow metering system including a pair of
co-located ultrasonic flowmeters coupled in series in accordance
with various embodiments;
[0011] FIG. 6 shows a block a diagram of a flow metering system
that includes co-located ultrasonic flowmeters in accordance with
various embodiments; and
[0012] FIG. 7 shows a flow diagram for a method for operating a
flow metering system that includes co-located ultrasonic flowmeters
in accordance with various embodiments.
NOTATION AND NOMENCLATURE
[0013] Certain terms are used throughout the following description
and claims to refer to particular system components. As one skilled
in the art will appreciate, companies may refer to a component by
different names. This document does not intend to distinguish
between components that differ in name but not function. In the
following discussion and in the claims, the terms "including" and
"comprising" are used in an open-ended fashion, and thus should be
interpreted to mean "including, but not limited to . . . ." In
addition, the term "couple" or "couples" is intended to mean either
an indirect or a direct electrical connection. Thus, if a first
device couples to a second device, that connection may be through a
direct electrical connection, or through an indirect electrical
connection via other devices and connections. Further, the term
"software" includes any executable code capable of running on a
processor, regardless of the media used to store the software.
Thus, code stored in memory (e.g., non-volatile memory), and
sometimes referred to as "embedded firmware," is included within
the definition of software. The recitation "based on" is intended
to mean "based at least in part on." Therefore, if X is based on Y,
X may be based on Y and any number of other factors. The term "flow
rate" as used herein refers to the rate of volumetric flow.
DETAILED DESCRIPTION
[0014] The following description is directed to various embodiments
of the invention. The drawing figures are not necessarily to scale.
Certain features of the embodiments may be shown exaggerated in
scale or in somewhat schematic form and some details of
conventional elements may not be shown in the interest of clarity
and conciseness. The disclosed embodiments should not be
interpreted, or otherwise used, to limit the scope of the
disclosure, including the claims. In addition, one skilled in the
art will understand that the following description has broad
application, and the discussion of any embodiment is meant only to
be exemplary of that embodiment, and not intended to intimate that
the scope of the disclosure, including the claims, is limited to
that embodiment. It is to be fully recognized that the different
teachings of the embodiments discussed below may be employed
separately or in any suitable combination to produce desired
results. Further, the various embodiments were developed in the
context of measuring hydrocarbon flows (e.g., crude oil, natural
gas), and the description follows from the developmental context;
however, the systems and methods described are equally applicable
to measurement of any fluid flow (e.g., cryogenic substances,
water).
[0015] FIG. 1 shows an ultrasonic flowmeter 100 in accordance with
various embodiments. The ultrasonic flowmeter 100 includes a meter
body or spool piece 102 that defines a central passage or bore 104.
The spool piece 102 is designed and constructed to be coupled to a
pipeline or other structure (not shown) carrying fluids (e.g.,
natural gas) such that the fluids flowing in the pipeline travel
through the central bore 104. While the fluids travel through the
central bore 104, the ultrasonic flowmeter 100 measures the flow
rate (hence, the fluid may be referred to as the measured fluid).
The spool piece 102 includes flanges 106 that facilitate coupling
of the spool piece 102 to another structure. In other embodiments,
any suitable system for coupling the spool piece 102 to a structure
may be equivalently used (e.g., weld connections).
[0016] In order to measure fluid flow within the spool piece 102,
the ultrasonic flowmeter 100 includes a plurality of transducer
assemblies. In the view of FIG. 1 five such transducers assembles
108, 110, 112, 116 and 120 are in full or partial view. The
transducer assemblies are paired (e.g., transducer assemblies 108
and 110), as will be further discussed below. Moreover, each
transducer assembly electrically couples to control electronics,
illustratively housed in enclosure 124. More particular, each
transducers assembly electrical couples to the control electronics
in the enclosure 124 by way of a respective cable 126 or equivalent
signal conducting assembly.
[0017] FIG. 2 shows a cross-sectional overhead view of the
ultrasonic flowmeter 100 taken substantially along line 2-2 of FIG.
1. Spool piece 102 has a predetermined size and defines the central
bore 104 through which the measured fluid flows. An illustrative
pair of transducers assemblies 112 and 114 is located along the
length of spool piece 102. Transducers 112 and 114 are acoustic
transceivers, and more particularly ultrasonic transceivers. The
ultrasonic transducers 112, 114 both generate and receive acoustic
signals having frequencies above about 20 kilohertz. The acoustic
signals may be generated and received by a piezoelectric element in
each transducer. To generate an ultrasonic signal, the
piezoelectric element is stimulated electrically by way of a signal
(e.g., a sinusoidal signal), and the element responds by vibrating.
The vibration of the piezoelectric element generates the acoustic
signal that travels through the measured fluid to the corresponding
transducer assembly of the pair. Similarly, upon being struck by an
acoustic signal, the receiving piezoelectric element vibrates and
generates an electrical signal (e.g., a sinusoidal signal) that is
detected, digitized, and analyzed by the electronics associated
with the flowmeter 100.
[0018] A path 200, also referred to as a "chord," exists between
illustrative transducer assemblies 112 and 114 at an angle .theta.
to a centerline 202. The length of chord 200 is the distance
between the face of transducer assembly 112 and the face of
transducer assembly 114. Points 204 and 206 define the locations
where acoustic signals generated by transducer assemblies 112 and
114 enter and leave fluid flowing through the spool piece 102
(i.e., the entrance to the spool piece bore). The position of
transducer assemblies 112 and 114 may be defined by the angle
.theta., by a first length L measured between the faces of the
transducer assemblies 112 and 114, a second length X corresponding
to the axial distance between points 204 and 206, and a third
length "d" corresponding to the pipe inside diameter. In most cases
distances d, X and L are precisely determined during flowmeter
fabrication. A measured fluid, such as natural gas, flows in a
direction 208 with a velocity profile 210. Velocity vectors 212,
214, 216 and 218 illustrate that the gas velocity through spool
piece 102 increases toward the centerline 202 of the spool piece
102.
[0019] Initially, downstream transducer assembly 112 generates an
ultrasonic signal that is incident upon, and thus detected by,
upstream transducer assembly 114. Some time later, the upstream
transducer assembly 114 generates a return ultrasonic signal that
is subsequently incident upon, and detected by, the downstream
transducer assembly 112. Thus, the transducer assemblies exchange
or play "pitch and catch" with ultrasonic signals 220 along chordal
path 200. During operation, this sequence may occur thousands of
times per minute.
[0020] The transit time of an ultrasonic signal 220 between
illustrative transducer assemblies 112 and 114 depends in part upon
whether the ultrasonic signal 220 is traveling upstream or
downstream with respect to the fluid flow. The transit time for an
ultrasonic signal traveling downstream (i.e., in the same direction
as the fluid flow) is less than its transit time when traveling
upstream (i.e., against the fluid flow). The upstream and
downstream transit times can be used to calculate the average
velocity along the signal path, and the speed of sound in the
measured fluid. Given the cross-sectional measurements of the
flowmeter 100 carrying the fluid, the average velocity over the
area of the central bore 104 may be used to find the volume of
fluid flowing through the spool piece 102.
[0021] Ultrasonic flowmeters can have one or more chords. FIG. 3
illustrates an end elevation view of ultrasonic flowmeter 100. In
particular, illustrative ultrasonic flowmeter 100 comprises four
chordal paths A, B, C and D at varying levels within the spool
piece 102. Each chordal path A-D corresponds to a transducer pair
behaving alternately as a transmitter and receiver. Transducer
assemblies 108 and 110 (only partially visible) make up chordal
path A. Transducer assemblies 112 and 114 (only partially visible)
make up chordal path B. Transducer assemblies 116 and 118 (only
partially visible) make up chordal path C. Finally, transducer
assemblies 120 and 122 (only partially visible) make up chordal
path D.
[0022] A further aspect of the arrangement of the four pairs of
transducers is shown with respect to FIG. 4, which shows an
overhead view. Each transducer pair corresponds to a single chordal
path of FIG. 3; however, the transducer assemblies are mounted at a
non-perpendicular angle to the center line 202. For example, a
first pair of transducer assemblies 108 and 110 is mounted at a
non-perpendicular angle .theta. to centerline 202 of spool piece
102. Another pair of transducer assemblies 112 and 114 is mounted
so that the chordal path loosely forms the shape of an "X" with
respect to the chordal path of transducer assemblies 108 and 110.
Similarly, transducer assemblies 116 and 118 are placed parallel to
transducer assemblies 108 and 110, but at a different "level" or
elevation. Not explicitly shown in FIG. 4 is the fourth pair of
transducer assemblies (i.e., transducer assemblies 120 and 122).
Considering FIGS. 2, 3 and 4, the transducers pairs may be arranged
such that the upper two pairs of transducers corresponding to
chords A and B form an the shape of an "X", and the lower two pairs
of transducers corresponding to chords C and D also form the shape
of an "X". The flow velocity of the fluid may be determined at each
chord A-D to obtain chordal flow velocities, and the chordal flow
velocities are combined to determine an average flow velocity over
the entire pipe. From the average flow velocity, the amount of
fluid flowing in the spool piece, and thus the pipeline, may be
determined.
[0023] Embodiments of the present disclosure couple a plurality of
ultrasonic flowmeters (e.g., instances 100A/B of the flowmeter 100)
to provide enhanced flow measurement accuracy. FIG. 5 shows a flow
metering system 500 including a pair of co-located ultrasonic
flowmeters 100 coupled in series. Other embodiments may include a
different number of coupled co-located flowmeters and/or a
different number of total or per flowmeter chordal paths. The
electronics of the pair of flowmeters are communicatively coupled
using a communication link 502, which may be a local area network
(LAN). The electronics of each flowmeter 100 exchanges flow
measurement values with the other flowmeter, and computes a
combined flow rate value based on flow measurements provided by
both meters 100. By combining the pair of four path meters 100, the
system 500 forms an eight path flowmeter that provides improved
measurement accuracy over each individual four path flowmeter 100
while allowing each flowmeter 100 to operate as a four path
flowmeter 100 should the other flowmeter 100 fail. In some
embodiments, the ultrasonic transducers of the two or more
flowmeters 100 may be disposed in a single spool piece and/or the
electronics of the two or meters may be disposed in a single
enclosure. In further embodiments, the two or more flowmeters 100
may include different chordal configurations, for example,
different chord elevations, angles, etc. relative to the flow path
that provide for improved measurement accuracy when the
measurements of the flowmeters 100 are combined.
[0024] FIG. 6 shows a block a diagram of the flow metering system
500 that includes co-located ultrasonic flowmeters 100A/B in
accordance with various embodiments. Each of the flowmeters 100
includes a set of transducer a pairs 602 (e.g., 108 and 110, 112
and 114, 116 and 118, 120 and 122) and electronics comprising a
transducer controller 604, a flow processor 606, and a
communications transceiver 608. Some embodiments may also include
one or more sensors 614 for measuring fluid attributes. The
transducer controller 604 is coupled to the transducer pairs 602,
and controls generation of ultrasonic signals by the transducer
pairs 602 by, for example, generating drive signals that induce
oscillation in the transducers. In some embodiments of the system
500, a transducer controller 604 of one of the flowmeters 100
generates a synchronization signal 610 that is provided to each of
the transducer controllers 604 of the other flowmeters 100. The
synchronization signal may be propagated by electrical conductors,
optical channels, wireless channels, etc.
[0025] The synchronization signal 610 establishes the timing of
ultrasonic signal generation by the meters 100, thereby preventing
ultrasonic signals generated by flowmeter 100A from interfering
with measurements made by flowmeter 100B and vice versa. In some
embodiments, the signal 610 specifies the start time and duration
for each transducer. In other embodiments, the signal 610, via
phase, voltage level, etc. may indicate a time period in which each
flowmeter 100 performs ultrasonic measurements free of interference
from other meters 100. In some embodiments, the synchronization
signal 610 is provided as a message transferred over a
communication link, e.g., link 502, between the meters 100. Other
embodiments of the system 500 may lack or selectively perform
transducer synchronization, for example, in embodiments where
interference is unlikely. In some embodiments, the ultrasonic
flowmeter 100 that controls transducer timing by generation of the
synchronization signal is termed "primary" and flowmeters 100
receiving the signal 610 are termed "secondary." The status of each
flowmeter 100 as primary or secondary may be established when the
flowmeter is manufactured or put into service.
[0026] The flow processor 606 is coupled to the transducer
controller 604, and is configured to process outputs of the
transducer pairs 602 to generate measurements of fluid flow within
the spool piece 102. For a given chord, the chordal flow velocity v
may be given by
v = L 2 2 X T up - T dn T up T dn ##EQU00001##
where: [0027] L is the path length (i.e., face-to-face separation
between upstream and downstream transducers), [0028] X is the
component of L within the flowmeter bore in the direction of the
flow, and [0029] T.sub.up and T.sub.dn are the upstream and
downstream transit times of sound energy through the fluid.
[0030] The flow processor 606 combines the chordal flow velocities
to determine an average flow velocity for the fluid flowing through
flowmeter 100, and computes the volumetric flow rate through the
flowmeter 100 as a product of the average flow velocity for the
flowmeter 100 and the cross-sectional area of the flowmeter
100.
[0031] The flow processor 606 may also compute an uncorrected flow
rate and a corrected flow rate. The uncorrected flow rate adjusts
the raw flow rate to account for the flow profile and fluid
expansion due to pressure and temperature. The corrected flow rate
adjusts the uncorrected flow rate to account for differences in
base and flow condition pressure, temperature, and fluid
compressibility.
[0032] Embodiments of the flow processor 606 are also configured to
compute flow through the spool piece 102 by combining flow
measurements provided by one flowmeter 100 with those provided by a
different flowmeter 100. Thus, the flow processor 606 of each
flowmeter 100 may be configured to produce combined flow
measurement values based on flow measurements generated by all
communicatively coupled flowmeters 100. The combined flow
measurements may be more accurate than the flow measurements
generated by any one of the meters 100 individually.
[0033] To generate a combined flow value, the flow processor 606 is
configured to periodically (e.g., a periodic flow computation time
interval--every 250 milliseconds (ms), every second, etc.) generate
ultrasonic signals, and compute one or more initial flow values
based on the outputs of the transducer pairs 602 controlled by the
flowmeter (e.g., the flowmeter 100A). The initial flow values may
include speed of sound along a chord, average speed of sound, flow
velocity along a chord, average flow velocity, flow measurement
quality, etc. The flow processor makes the initial flow values
available for retrieval by other meters 100 in real-time (i.e., the
time period (e.g., 250 ms) set for generating flow values by the
meter 100 is unaffected by the retrieval and associated
operations). In some embodiments, the flow processor 606 provides
the initial flow values to a server disposed in the flowmeter 100A.
The server is configured to process requests from another flowmeter
100 for the initial flow values computed by the flowmeter 100A, and
provide the initial flow values to the other flowmeter 100
responsive to the request. The flow processor may also provide, for
retrieval by other meters 100, an expiration time value that
defines the time interval during which initial flow values are
considered valid.
[0034] The flow processor 606 generates a message requesting
initial flow values from a different flowmeter 100, and transmits
the message via the communication transceiver 608. The transceiver
608 is communicatively linked to instances of the transceiver 608
in other meters 100. The transceiver 608 may be, for example,
configure to provide communication in accordance with a networking
standard, such as IEEE 802.3, IEEE 802.11, etc. The instance of the
flowmeter 100 receiving the message (e.g., the flowmeter to which
the message is addressed by internet protocol address) provides the
requested initial flow values to the requesting flowmeter 100 via a
message transferred over the communication link formed by the
transceivers 608.
[0035] The flow processor 606 verifies the initial flow values
received from the other flowmeter 100. For example, the flow
processor 606 may verify that the expiration time value associated
with the flow values has not expired, that a provided flow
measurement quality value indicates valid measurements, that
message check characters indicate valid data, etc. If the
verification indicates that the initial flow values are valid, then
the flow processor 606 combines the initial flow values provided by
the other flowmeter 100 with the initial flow values computed by
the flow processor 606 to generate a combined flow value. Some
embodiments may combine the initial flow values by computing an
average of the initial flow values generated by each flowmeter 100.
The flow processor 606 may compute fluid flow rate (raw, corrected,
uncorrected), flow volume, flow mass, etc. based on the combined
flow value.
[0036] The flow processor 606 may store the combined flow value
and/or the flow rate derived from the combined flow value in
memory, provide the value to a database, and/or generate signals
representative of flow rate, flow volume, etc. based on the
combined flow value. For example, some embodiments of the flow
processor 606 may generate an output signal having a frequency
representative of a flow rate derived from the combined flow
value.
[0037] If the flow processor 606 of the flowmeter 100A (or any
flowmeter 100) is unable to verify the initial flow values received
from another flowmeter 100, then the flow processor 606 may compute
a final flow value based on only the initial flow values produced
by the flowmeter 100A. Thus, the system 500 provides redundancy in
that each flowmeter 100 can provide flow measurements based on the
outputs of only the transducer pairs 602 of the flowmeter 100 when
other instances of the flowmeter 100 fail, and provide enhanced
flow measurement accuracy based on the outputs of all transducer
pairs 602 when all of the meters 100 are operating properly.
[0038] Some embodiments of the flowmeter 100 also include sensors
614 that measure attributes of the fluid flowing in the spool piece
102. The sensors 614 may include, for example, one or more of a
temperature sensor, a pressure sensor, and a gas composition sensor
that measure fluid temperature, fluid pressure, and fluid
composition respectively. The sensor measurement values may be
shared between meters 100 as described above with regard to initial
flow values. The meters 100 may apply the sensor measurement values
to improve the accuracy of the computed flow values, flow rates,
etc.
[0039] Various components of the flowmeter 100 including at least
some portions of the flow processor 606 and the transducer
controller 604 can be implemented using a processor, included in
the flowmeter 100. The processor executes software programming that
causes the processor to perform the operations described herein. In
some embodiments, the flow processor 606 includes a processor
executing software programming that causes the processor to
generate flow values, such as the initial flow values, combined
flow values, flow rates, etc., and perform other operations
described herein.
[0040] Suitable processors include, for example, general-purpose
microprocessors, digital signal processors, and microcontrollers.
Processor architectures generally include execution units (e.g.,
fixed point, floating point, integer, etc.), storage (e.g.,
registers, memory, etc.), instruction decoding, peripherals (e.g.,
interrupt controllers, timers, direct memory access controllers,
etc.), input/output systems (e.g., serial ports, parallel ports,
etc.) and various other components and sub-systems. Software
programming that causes a processor to perform the operations
disclosed herein can be stored in a computer readable storage
medium internal or external to the flowmeter 100. A computer
readable storage medium comprises volatile storage such as random
access memory, non-volatile storage (e.g., a hard drive, an optical
storage device (e.g., CD or DVD), FLASH storage, read-only-memory,
or combinations thereof.
[0041] Some embodiments can implement portions of the ultrasonic
flowmeter 100, including portions of the flow processor 606 and
transducer controller 604, using dedicated circuitry (e.g.,
dedicated circuitry implemented in an integrated circuit). Some
embodiments may use a combination of dedicated circuitry and a
processor executing suitable software. For example, some portions
of the transducer controller 604 may be implemented using a
processor or hardware circuitry. Selection of a hardware or
processor/software implementation of embodiments is a design choice
based on a variety of factors, such as cost, time to implement, and
the ability to incorporate changed or additional functionality in
the future.
[0042] FIG. 7 shows a flow diagram for a method 700 for operating a
flow metering system 500 that includes co-located ultrasonic
flowmeters 100 in accordance with various embodiments. Though
depicted sequentially as a matter of convenience, at least some of
the actions shown can be performed in a different order and/or
performed in parallel. Additionally, some embodiments may perform
only some of the actions shown. In some embodiments, the operations
of FIG. 7, as well as other operations described herein, can be
implemented as instructions stored in a computer readable medium
and executed by processors included in the meters 100.
[0043] In the method 700, a plurality of ultrasonic flowmeters 100
are co-located (e.g., serially connected or disposed in a single
spool piece) and each flowmeter 100 is generating flow values based
on the ultrasonic transducer pairs 602 of all of the flowmeters. In
block 702, the generation of ultrasonic signals by the transducers
of the plurality of flowmeters 100 is synchronized to reduce
interference between the flowmeters 100. One of the flowmeters 100
may be designated the primary flowmeter and generate the
synchronization signal 610 that is provided to each of the other
co-located flowmeters to effect the synchronization.
[0044] Each flowmeter 100 generates ultrasonic signals in block
704. The signals traverse the interior of the spool piece 102, and
are detected by an ultrasonic transducer. Electrical signals
representative of the detected ultrasonic signals are provided to
the flow processor 606.
[0045] In block 706, sensors 614 measure attributes of the fluid
flowing in the spool piece 102, such as fluid temperature, fluid
pressure, fluid composition, etc. The attribute measurements are
provided to the flow processor 606 for use in computing fluid
flow.
[0046] In block 708, each flowmeter 100, computes a set of initial
flow values. The initial flow values are based on the ultrasonic
signals generated and detected only by the transducer pairs 602 of
the flowmeter 100. In some embodiments, the initial flow values may
also be based on the fluid attributes measured by the sensors. The
initial flow values may include an average speed of sound, average
flow velocity, flow rate value, etc. for the flowmeter 100.
[0047] In block 710, the initial flow values, and optionally the
sensor measurements, are made accessible to co-located meters 100.
For example, the initial flow values may be provided to a server in
the flowmeter 100, and each of the co-located meters 100 operates
as a client of the server to access the initial flow values via the
communication link 502.
[0048] In block 712, each flowmeter 100 retrieves initial flow
values from each other co-located flowmeter 100. Retrieval may
include generating a request message that is communicated to each
other flowmeter 100 (e.g., to a server included in each flowmeter
100). On receipt of the request message, each flowmeter 100 may
generate a response message that includes the initial flow values,
and transfer the response message to the requesting flowmeter
100.
[0049] In block 714, each flowmeter 100 verifies the initial flow
values received from the other co-located meters 100. The
verification may include computation of check values (such as
cyclic redundancy check values) applied to the initial flow values,
verification that a flow value lifetime value has not expired, and
verification that the quality of the flow measurements exceeds a
predetermined threshold.
[0050] In block 716, if a flowmeter 100 finds the retrieved initial
flow values to be invalid, then, in block 718, the some embodiments
of the flowmeter 100 compute a final flow rate value based only on
the flow information generated by the flowmeter 100 (i.e., an
individual final flow value). The individual final flow value is
not based on initial flow values generated by other co-located
meters 100. The flowmeter 100 also generates a fluid flow rate
based on the individual final flow value.
[0051] If, in block 716, a flowmeter 100 finds the retrieved
initial flow values to be valid, then, in block 720, the flowmeter
100 computes a final flow value based on the initial flow values
generated by the plurality of co-located meters 100 (i.e., a
combined final flow value). The flowmeter 100 applies the combined
final flow value to generate a fluid flow rate based on the total
number of chordal paths provided all of the co-located meters 100.
The fluid flow rate may also be based on the sensor measurements
retrieved from one or more of the co-located meters 100.
[0052] In block 722, the final flow value, which may be the
individual or combined final flow rate explained above, and a flow
rate based on the final flow value is stored for access by other
components of the flow measurement system (e.g., access by a user
interface/display/input sub-system or a flow control system). A
signal representative of the flow rate may also be generated for
communication of the flow rate to other equipment.
[0053] The above discussion is meant to be illustrative of various
embodiments of the present invention. Numerous variations and
modifications will become apparent to those skilled in the art once
the above disclosure is fully appreciated. For example, while
embodiments of the invention have been discussed with relation to a
pair of co-located ultrasonic flowmeters, those skilled in the art
will understand that embodiments are applicable to any number of
co-located flowmeters. Furthermore, while embodiments have been
discussed with regard to flowmeters having four chordal paths,
those skilled in the art will understand that embodiments encompass
flowmeters having any number of chordal paths, including co-located
flowmeters each having a different number of chordal paths. It is
intended that the following claims be interpreted to embrace all
such variations and modifications.
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